* Xi warns that mishandling Taiwan issue could lead to

conflict

* Leaders will meet again on last day of Trump's visit

* US officials tout deals on farm goods, beef and Boeing ( BA )

jets

* Trump seeks Chinese help on opening Strait of Hormuz

By Trevor Hunnicutt and Liz Lee

BEIJING, May 15 (Reuters) - U.S. President Donald Trump

and China's Xi Jinping are set to meet on Friday to wrap up a

two-day state visit that has featured pomp and business deals

but also a warning from Xi that mishandling the Taiwan issue

could send relations spiraling.

Trump is on the first visit by a U.S. president to China,

America's main strategic and economic rival, since his last in

2017, and has been seeking tangible results to beef up his

dented approval ratings ahead of crucial midterm elections.

"Hopefully our relationship with China will be stronger and

better than ever before!" Trump wrote in a post on his Truth

Social platform early on Friday.

He described Xi as a "warm person" but "all business" in a

pre-recorded interview on Fox News' 'Hannity' program.

Trump and Xi are set to have tea and lunch at the walled-off

Zhongnanhai complex, a former imperial garden that houses the

offices of Chinese leaders, before Trump departs.

The summit has been aimed at maintaining a fragile trade

truce struck when the leaders last met in October and Trump

suspended triple-digit tariffs on Chinese goods and Xi backed

away from choking global supplies of vital rare earths.

On Thursday, Xi told Trump that negotiations on trade issues

had reached "balanced and positive outcomes", without

elaborating.

U.S. Trade Representative Jamieson Greer, who is with Trump

in China, told Bloomberg TV on Friday it had not yet been

decided whether to extend the truce beyond its expiry later this

year.

Deals on Chinese purchases of farm goods, beef and Boeing ( BA )

aircraft have been firmed up, Greer added, and progress was made

on establishing mechanisms to manage future trade, with both

sides expected to identify $30 billion of non-sensitive goods.

The Taiwan issue should not push that off the rails, he

said.

Trump told Fox News that China had agreed to order 200

Boeing ( BA ) jets, its first purchase of U.S.-made commercial

jets in nearly a decade. That was far short of the roughly 500

markets had expected, and Boeing ( BA ) shares fell more than 4% after

the comments.

U.S. export controls on semiconductor chips were not a major

discussion, Greer said in comments that suggest a breakthrough

on selling Nvidia's ( NVDA ) advanced H200 chips to China

remains far away, despite CEO Jensen Huang's last-minute

addition to the trip.

Trump has also been expected to urge China to convince Iran

to make a deal with Washington to end a war unpopular with

American voters.

But his hand has been weakened in Beijing, after U.S. courts

curbed his ability to levy tariffs at will and price increases

driven by the Iran war have made him politically vulnerable at

home.

A brief U.S. summary of Thursday's talks highlighted what

the White House called the leaders' shared desire to reopen the

Strait of Hormuz off Iran and Xi's apparent interest in American

oil purchases to pare China's dependence on Middle East supply.

A fifth of global supplies of oil and liquefied natural gas

travel through the Strait in normal times.

"President Xi would like to see a deal made," Trump told Fox

News. "And he did offer. He said, 'If I can be of any help at

all, I would like to be of help.'"

STARK WARNING

Xi's remarks on Taiwan, the democratically governed island

Beijing claims, delivered a sharp, if not unprecedented, warning

during a summit that otherwise appeared friendly and relaxed.

Taiwan, which lies just 50 miles (80 km) off China's coast,

has long been a flashpoint in U.S.-China ties, with Beijing

refusing to rule out the use of military force to gain control

of the island and the United States bound by law to provide

Taipei with the means to defend itself.

"U.S. policy on the issue of Taiwan is unchanged as of

today," Secretary of State Marco Rubio, who is also traveling

with Trump, told NBC News, adding the Chinese "always raise it

... we always make clear our position and we move on."

Taiwan Foreign Minister Lin Chia-lung thanked the United

States on Friday for repeatedly expressing its support.

The China-U.S. relationship is the most important in the

world, Xi said at Thursday's lavish state banquet, adding, "We

must make it work and never mess it up."

JAILED CHINA CRITIC JIMMY LAI

Rubio said Trump had brought up with Xi the issue of Hong

Kong's most vocal China critic, media tycoon Jimmy Lai,

sentenced in February to 20 years in jail in the Asian financial

hub's biggest national security case.

"The president always raises that case and a couple others,

and obviously we'll hope to get a positive response from that,"

Rubio told NBC News.

"We'd be open to any arrangement that would work for them,

as long as he's given his freedom," he said of Lai, who has

denied all the charges against him.

Hong Kong affairs are an internal matter for China, the

foreign ministry has said previously when asked about Lai.